1. Field of the Invention
The present invention relates generally to hard copy printing devices, such as computer printers and plotters, fax machines, and the like, more particularly, to ink-jet type ink cartridge devices, and, more specifically, to an improved ink-jet cartridge for a thermal ink-jet pen.
2. Description of the Related Art
The art of thermal ink-jet printing is relatively well-developed. The basics are disclosed, for example, in various articles in the Hewlett-Packard Journal, May 1985, August 1988, October 1988, August 1992, and December 1992 editions, incorporated herein by reference.
In the art, it is known to provide a scanning printhead having a nozzle plate in combination with heating elements. Thermal excitation of ink is used to eject droplets through tiny nozzles, or "orifices," onto a print media. The nozzle plate configuration is one of the design factors that controls droplet size, velocity and trajectory of the droplets. The state-of-the-art has progressed to the state where ink-jet printers provide near-laser print quality by providing resolution up to 1200 dots per inch ("dpi").
Another important design factor in thermal ink-jet technology is the storage and delivery of ink from a reservoir to the nozzle plate of the printhead. In general, problems of fluid dynamics, ink containment, handling and leakage, ink mixing in multi-reservoir pens, printhead clogging due to ink supply contamination, air ingestion and entrapment, pen priming, printhead back pressure, and others are of major concern to those skilled in the art.
Various types of ink reservoirs have been used, including both disposable and refillable ink reservoir cartridges. In one type, the reservoir is integrated with the pen and mounted on a moveable printer carriage for scanning across the print media. In another, a remote, or "off-board," ink reservoir is provided from which ink is drawn to the printhead through a tubing system. The latter is demonstrated, for example, in U.S. Pat. No. 4,422,084, (Saito) in FIGS. 2 and 3, labeled "Prior Art." It has been found in general that the relatively long tubing used to convey ink from an off-board reservoir to a printhead does not lend itself well for different printing pressure ranges. Such complicated systems exacerbate the problems associated with delivery of ink from a reservoir to a printhead.
Several designs and features of integrated pens are disclosed by the common assignee of the present application in the following co-pending applications, incorporated herein by reference:
NEGATIVE PRESSURE INK DELIVERY SYSTEM, Ser. No. 07/995,851, filed Dec. 23, 1992, (Kaplinsky, et al.); abandoned PA1 COMPACT FLUID COUPLER FOR THERMAL INK JET PRINT CARTRIDGE AND RESERVOIR, Ser. No. 07/853,372, filed Mar. 18, 1992, (Salter); PA1 INK PRESSURE REGULATOR FOR A THERMAL INK-JET PRINTER, Ser. No. 07/928,811, filed Aug. 12, 1992, (Khodapanah et al.); PA1 TWO MATERIAL FRAME HAVING DISSIMILAR PROPERTIES FOR A THERMAL INK-JET CARTRIDGE, Ser. No. 07/994,807, filed Aug. 12, 1992, (Swanson et al.); PA1 RIGID LOOP CASE STRUCTURE FOR THERMAL INK-JET PEN, Ser. No. 07/994,808, filed Dec. 22, 1992, (Swanson et al.); PA1 THERMAL INK-JET PEN WITH A PLASTIC/METAL ATTACHMENT FOR THE COVER, Ser. No. 07/994,810, filed Aug. 12, 1992, (Timm et al.); PA1 THIN PEN STRUCTURE FOR THERMAL INK-JET PRINTER, Ser. No. 07/994,809, filed Dec. 22, 1992, (Swanson et al.); PA1 DOUBLE COMPARTMENT INK-JET CARTRIDGE WITH OPTIMUM SNOUT, Ser. No. 07/995,221, filed Dec. 22, 1992, (Swanson et al.); PA1 LAMINATED FILM INK RESERVOIR, Ser. No. 07/995,868, filed Dec. 23, 1992, (Scheffelin); PA1 TWO MATERIAL FRAME HAVING DISSIMILAR PROPERTIES FOR THERMAL INK-JET CARTRIDGE, Ser. No. 08/058,730, filed May 3, 1993, (Chundury); PA1 SPRING BAG PRINTER INK CARTRIDGE WITH VOLUME INDICATOR, Ser. No. 07/717,735, filed Jun. 19, 1991, (Hunt et al.); U.S. Pat. No. 5,359,353, and PA1 PRINTER INK CARTRIDGE, Ser. No. 08/170,951, (Gragg, et al.), filed concurrently herewith.
There is a need to provide an ink cartridge which reliably delivers a steady flow of liquid ink to the printhead but which is capable of withstanding the rigors of high-speed computer printing operations and the design problems associated with high-speed scanning of a pen across the print media.